import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep

"""响应按键"""
def check_keydown_events(event,ai_settings,screen,ship,bullets):
    if event.key == pygame.K_RIGHT:
        #向右移动飞船
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        #向左移动飞船
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings,screen,ship,bullets)
    elif event.key == pygame.K_q:
        sys.exit()
        
"""响应松开"""
def check_keyup_events(event,ship):
    if event.key == pygame.K_RIGHT:
        #停止右移动飞船
        ship.moving_right = False
    elif event.key == pygame.K_LEFT:
        #停止左移动飞船
        ship.moving_left = False

def check_events(ai_settings,stats,play_button,sb,screen,ship,aliens,bullets):  
    """响应按键和鼠标事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event,ai_settings,screen,ship,bullets)
        elif event.type == pygame.KEYUP:
            check_keyup_events(event,ship)
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x,mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings,stats,play_button,sb,screen,ship,aliens,bullets,mouse_x,mouse_y)

def check_play_button(ai_settings,stats,play_button,sb,screen,ship,aliens,bullets,mouse_x,mouse_y):
    """在玩家单机play按钮时开始游戏"""
    button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)
    if button_clicked and not stats.game_active:
        #重置游戏设置
        ai_settings.initialize_dynamic_settings()
        #隐藏光标
        pygame.mouse.set_visible(False)
        
        #重新游戏统计信息
        stats.reset_stats()
        stats.game_active = True

        #重置积分牌图像
        sb.prep_level()
        sb.prep_high_score()
        sb.prep_score()
        sb.prep_ships()

        #清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        #创建一群新的外星人，并让飞船居中
        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()
    

"""刷新屏幕"""
def update_screen(ai_settings,stats,sb,screen,ship,aliens,bullets,play_button):
    """更新屏幕上的图像，并切换到新屏幕"""
    #每次循环都重新绘制屏幕
    screen.fill(ai_settings.bg_color)
    sb.show_score()
    ship.blitme()
    aliens.draw(screen)

    #在飞船和外星人后绘制所有子弹
    for bullet in bullets:
        bullet.blitme()

    #如果游戏处于非活动状态，就绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()

    #让最近绘制的屏幕可见
    pygame.display.flip()

def update_bullets(ai_settings,stats,sb,screen,ship,aliens,bullets):
    """更新子弹的位置，并删除消失的子弹"""
    #更新子弹的位置
    bullets.update()

    #删除已经消失的子弹
    for bullet in bullets.copy():
        if bullet.rect.bottom < 0:
            bullets.remove(bullet)
    check_aliens_bullets_collisions(ai_settings,stats,sb,screen,ship,aliens,bullets)
    

def update_alien(ai_settings,stats,sb,screen,ship,aliens,bullets):
    """检查是否有外星人位于屏幕边缘，并更新外星人的位置"""
    check_fleet_edges(ai_settings,aliens)
    aliens.update()

    #检测外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship,aliens):
        ship_hit(ai_settings,stats,screen,ship,aliens,bullets)

    check_aliens_bottom(ai_settings,stats,sb,screen,ship,aliens,bullets)
    
def check_aliens_bullets_collisions(ai_settings,stats,sb,screen,ship,aliens,bullets):
    #检查是否有子弹击中了外星人
    #如果击中，就删除对应的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)

    if collisions:
        for aliens in collisions.values():
            stats.score += ai_settings.alien_points * len(aliens)
            sb.prep_score()
        check_high_score(stats,sb)
        
    if len(aliens) == 0:
        #删除所有子弹新建一群外星人
        bullets.empty()
        ai_settings.increase_speed()

        #提高等级
        stats.level += 1
        sb.prep_level()

        create_fleet(ai_settings,screen,ship,aliens)

def check_aliens_bottom(ai_settings,stats,sb,screen,ship,aliens,bullets):
    #检查是否有外星人到达屏幕底端
    screen_rect = screen.get_rect()
    for alien in aliens:
        if alien.rect.bottom > screen_rect.bottom:
            #飞船坠毁 
            ship_hit(ai_settings,stats,sb,screen,ship,aliens,bullets)
            break

def ship_hit(ai_settings,stats,sb,screen,ship,aliens,bullets):
    """响应被外星人撞到的飞船"""
    if stats.ships_left > 0 :
        #将ship_left减1
        stats.ships_left -= 1

        #更新计分牌
        sb.prep_ships()

        #清空外星人和子弹列表   
        aliens.empty()
        bullets.empty()

        #创建新的外星人，并将飞船移动到中央
        create_fleet(ai_settings,screen,ship,aliens)
        ship.center_ship()

        #暂停
        sleep(0.5)
    else:
        stats.game_active = False
        #重新显示光标
        pygame.mouse.set_visible(True)

def fire_bullet(ai_settings,screen,ship,bullets):
    """根据子弹限制创建新子弹对象"""
    if len(bullets) < ai_settings.bullets_allowed:
            new_bullet = Bullet(ai_settings,screen,ship)
            bullets.add(new_bullet)

def get_number_aliens_x(ai_settings,alien_width):
    """计算每行可容纳多少个外星人"""
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x/(2*alien_width))
    return number_aliens_x

def get_number_rows(ai_settings,ship_heigh,alien_heigh):
    """计算屏幕可以容纳多少行外星人"""
    avaliable_space_y = (ai_settings.screen_height - 3 * alien_heigh - 2 *  ship_heigh)
    number_rows = int(avaliable_space_y/(2 * alien_heigh))
    return number_rows

def creat_alien(ai_settings,screen,aliens,alien_number,number_row):
    """创建一个外星人并将其放在当前行"""
    alien = Alien(ai_settings,screen)
    alien_width = alien.rect.width
    alien_heigh = alien.rect.height
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.y =  100 + alien_heigh + 2 * alien_heigh * number_row
    alien.rect.x = alien.x
    alien.rect.y = alien.y
    aliens.add(alien)

def create_fleet(ai_settings,screen,ship,aliens):
    """创建外星人群"""
    #创建一个外形人，并计算一行可容纳多少个外星人
    #外星人间距为外星人宽度
    alien = Alien(ai_settings,screen)
    number_aliens_x = get_number_aliens_x(ai_settings,alien.rect.width)
    number_rows = get_number_rows(ai_settings,ship.rect.height,alien.rect.height)
    #创建一行外星人
    for number_row in range(number_rows):
        for alien_number in range(number_aliens_x):
            creat_alien(ai_settings,screen,aliens,alien_number,number_row)

def check_fleet_edges(ai_settings,aliens):
    """有外星人到达边缘时采取相应的措施"""
    for alien in aliens:
        if alien.check_edges():
            change_fleet_direction(ai_settings,aliens)
            break

def change_fleet_direction(ai_settings,aliens):
    """将整群外星人下移，并改变他们的方向"""
    for alien in aliens.copy():
        alien.rect.y += ai_settings.fleet_dorp_speed
    ai_settings.fleet_direction *= -1

def check_high_score(stats,sb):
    """检查是否诞生了新的最高分"""
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()